6 resultados para Modelo de coordenada de conjugação efetiva

em Universidade Federal do Rio Grande do Norte(UFRN)


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Parkinson disease (PD) is associated with motor symptoms and dopaminergic cell loss in the nigrostriatal pathway. Alpha-synuclein is the major component of the Lewy bodies, the biological hallmarks of disease, and has been associated with familial cases of PD. Recently, the spinal cord stimulation (SCS) showed to be effective to alleviate the Parkinson symptoms in animal models and human patients. In this project, we characterized the motor and electrophysiological effects of alpha-synuclein overexpression in the substantia nigra of rats. We further investigated the effects of spinal electrical stimulation, AMPT and L-dopa administration in this model. Method: Sprague-Dawley rats were injected with empty viral vector or the vector carrying the gene for alpha-synuclein in the substantia nigra, and were tested weekly for 10 weeks in the open field and cylinder tests. A separated group of animals implanted with bilateral electrode arrays in the motor cortex and the striatum were recorded in the open field, during the SCS sessions and the pharmacological experiments. Results: Alpha-synuclein expression resulted in motor asymmetry, observed as the reduction in use of contralateral forepaw in the cylinder test. Animals showed an increase of local field potential activity in beta band three and four weeks after the virus injection, that was not evident after the 5th week. AMPT resulted in a sever parkinsonian state, with reduction in the locomotor activity and significant peak of oscillatory activity in cortex and striatum. SCS was effective to alleviate the motor asymmetry at long term, but did not reduce the corticostriatal low frequency oscillations observed 24 hs after the AMPT administration. These oscillations were attenuated by L-dopa that, even as SCS, was not effective to restore the locomotor activity during the severe dopaminergic depletion period. Discussion: The alpha-synuclein model reproduces the motor impairment and the progressive neurodegenerative process of PD. We demonstrated, by the first time, that this model also presents the increase in low frequency oscillatory activity in the corticostriatal circuit, compatible with parkinsonian condition; and that SCS has a therapeutic effect on motor symptom of this model.

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Ceramic filters are cellular structures that can be produced by various techniques, among which we highlight the replication method, or method of polymeric sponge. This method consists of impregnating polymeric foam with ceramic slurry, followed by heat treatment, where will occur decomposition of organic material and the sinter of the ceramic material, resulting in a ceramic whose structure is a replica of the impregnated sponge. Ceramic filters have specific properties that make this type of material very versatile, used in various technological applications such as filters for molten metals and burners, make these materials attractive candidates for high temperature applications. In this work we studied the systems Al2O3-LZSA ceramic filters processed in the laboratory, and commercial Al2O3-SiC ceramics filters, both obtained by the replica method, this work proposes the thermal and mechanical characterization. The sponge used in the processing of filters made in the laboratory was characterized by thermogravimetric analysis. The ceramic filters were characterized by compressive strength, flexural strength at high temperatures, thermal shock, permeability and physical characterization (density and porosity) and microstructural (MEV and X-rays). From the results obtained, the analysis was made of the mechanical behavior of these materials, comparing the model proposed by Gibson and Ashby model and modified the effective area and the tension adjusted, where the modified model adapted itself better to the experimental results, representing better the mechanical behavior of ceramic filters obtained by the replica method

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Many pollutants dumped in waterways, such as dyes and pesticides, have become so ubiquitous that they represent a serious threat to human health. The electrochemical oxidation is presented as an alternative clean, efficient and economic degradation of wastewater containing organic compounds and a number of advantages of this technique is to just not make use of chemical reagents, since only electrical energy is consumed during the removal of pollutants organic. However, despite being a promising alternative, still needs some tweaking in order to obtain better efficiency in the elimination of persistent pollutants. Thus, this study sought a relationship between a recently discovered phenomenon that reflects the participation of dissolved oxygen in solution in the electrochemical oxidation process, as an anomaly, present a kinetic model that shows instantaneous current efficiency (ICE) above 100% limited by theory, manifested for some experiments with phenolic compounds with H2SO4 or HClO4 as supporting electrolyte with electrodes under anodic oxidation on boron doped diamond (BDD). Therefore it was necessary to reproduce the data ICE exposes the fault model, and thus the 2-naphthol was used as phenolic compound to be oxidised at concentrations of 9, 12 and 15 mmol L-1, and H2SO4 and HClO4 to 1 mol L-1 as a supporting electrolyte under a current density of 30 mA cm-2 in an electrochemical reactor for continuous flow disk configuration, and equipped with anodes DDB at room temperature (25 oC). Experiments were performed using N2 like as purge gas for eliminate oxygen dissolved in solution so that its influence in the system was studied. After exposure of the anomaly of the ICE model and investigation of its relationship with dissolved O2, the data could be treated, making it possible for confirmation. But not only that, the data obtained from eletranálise and spectroscopic analysis suggest the involvement of other strongly oxidizing species (O3 (ozone) and O radicals and O2 -), since the dissolved O2 can be consumed during the formation of new strong oxidizing species, not considered until now, something that needs to be investigated by more accurate methods that we may know a little more of this system. Currently the performance of the electrocatalytic process is established by a complex interaction between different parameters that can be optimized, so it is necessary to the implementation of theoretical models, which are the conceptual lens with which researchers see

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Ceramic filters are cellular structures that can be produced by various techniques, among which we highlight the replication method, or method of polymeric sponge. This method consists of impregnating polymeric foam with ceramic slurry, followed by heat treatment, where will occur decomposition of organic material and the sinter of the ceramic material, resulting in a ceramic whose structure is a replica of the impregnated sponge. Ceramic filters have specific properties that make this type of material very versatile, used in various technological applications such as filters for molten metals and burners, make these materials attractive candidates for high temperature applications. In this work we studied the systems Al2O3-LZSA ceramic filters processed in the laboratory, and commercial Al2O3-SiC ceramics filters, both obtained by the replica method, this work proposes the thermal and mechanical characterization. The sponge used in the processing of filters made in the laboratory was characterized by thermogravimetric analysis. The ceramic filters were characterized by compressive strength, flexural strength at high temperatures, thermal shock, permeability and physical characterization (density and porosity) and microstructural (MEV and X-rays). From the results obtained, the analysis was made of the mechanical behavior of these materials, comparing the model proposed by Gibson and Ashby model and modified the effective area and the tension adjusted, where the modified model adapted itself better to the experimental results, representing better the mechanical behavior of ceramic filters obtained by the replica method

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The knowledge management has received major attention from product designers because many of the activities within this process have to be creative and, therefore, they depend basically on the knowledge of the people who are involved in the process. Moreover, Product Development Process (PDP) is one of the activities in which knowledge management manifests in the most critical form once it had the intense application of the knowledge. As a consequence, this thesis analyzes the knowledge management aiming to improve the PDP and it also proposes a theoretical model of knowledge management. This model uses five steps (creation, maintenance, dissemination, utilization and discard) through the verification of the occurrence of four types of knowledge conversion (socialization, externalization, combination and internalization) that it will improve the knowledge management in this process. The intellectual capital in Small and Medium Enterprises (SMEs) managed efficiently and with the participation of all employees has become the mechanism of the creation and transference processes of knowledge, supporting and, consequently, improving the PDP. The expected results are an effective and efficient application of the proposed model for the creation of the knowledge base within an organization (organizational memory) aiming a better performance of the PDP. In this way, it was carried out an extensive analysis of the knowledge management (instrument of qualitative and subjective evaluation) within the Design department of a Brazilian company (SEBRAE/RN). This analysis aimed to know the state-of-the-art of the Design department regarding the use of knowledge management. This step was important in order to evaluate in the level of the evolution of the department related to the practical use of knowledge management before implementing the proposed theoretical model and its methodology. At the end of this work, based on the results of the diagnosis, a knowledge management system is suggested to facilitate the knowledge sharing within the organization, in order words, the Design department

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The knowledge management has received major attention from product designers because many of the activities within this process have to be creative and, therefore, they depend basically on the knowledge of the people who are involved in the process. Moreover, Product Development Process (PDP) is one of the activities in which knowledge management manifests in the most critical form once it had the intense application of the knowledge. As a consequence, this thesis analyzes the knowledge management aiming to improve the PDP and it also proposes a theoretical model of knowledge management. This model uses five steps (creation, maintenance, dissemination, utilization and discard) through the verification of the occurrence of four types of knowledge conversion (socialization, externalization, combination and internalization) that it will improve the knowledge management in this process. The intellectual capital in Small and Medium Enterprises (SMEs) managed efficiently and with the participation of all employees has become the mechanism of the creation and transference processes of knowledge, supporting and, consequently, improving the PDP. The expected results are an effective and efficient application of the proposed model for the creation of the knowledge base within an organization (organizational memory) aiming a better performance of the PDP. In this way, it was carried out an extensive analysis of the knowledge management (instrument of qualitative and subjective evaluation) within the Design department of a Brazilian company (SEBRAE/RN). This analysis aimed to know the state-of-the-art of the Design department regarding the use of knowledge management. This step was important in order to evaluate in the level of the evolution of the department related to the practical use of knowledge management before implementing the proposed theoretical model and its methodology. At the end of this work, based on the results of the diagnosis, a knowledge management system is suggested to facilitate the knowledge sharing within the organization, in order words, the Design department